Britain's leading sex therapists have launched a scathing attack on a Channel 4 series in which couples' sexual techniques are given a makeover, saying it could cause viewers psychological damage.

Britain's leading sex therapists have launched a scathing attack on a Channel 4 series in which couples' sexual techniques are given a makeover, saying it could cause viewers psychological damage.

They claim Tracey Cox, a broadcaster and writer, is out of her depth and unqualified as an adviser on The Sex Inspectors in which volunteers invite cameras into the bedroom to transform their love lives.

The series, which begins next week, was commissioned before chief executive Mark Thompson took over as BBC director general. Couples were filmed having sex, then given tips on how to improve their technique, though the use of heat-sensitive cameras and blurring will prevent graphic images being screened.

Dr Petra Boynton, a lecturer in health services research at University College London, claimed Ms Cox, who is not qualified as a therapist, was dabbling in complex areas that should be left to experts.

Phillip Hodson, a fellow of the British Association for Counselling and Sex Therapy, who reviewed the programme for The Independent on Sunday, said he was concerned the show misrepresented what counts as normal sex. "I fear that we are now going to be faced with a whole new battery of false sex norms in the consulting room as a result of the Cox Factor," he said.

Mr Hodson said the "amateurishness" on screen showed, and he questioned "the ethics of calling someone a sexual expert" when they had no recognised qualification in that field. Ms Cox, 43, has acted as a relationship expert for the BBC series Would Like to Meet and written books such as Hot Sex and Superflirt. The psychology graduate and former editor of Australian Cosmopolitan is joined on the show by Michael Alvear, a gay American agony uncle.

Ms Cox said: "I treat sex very carefully, but I think after 20 years dealing with the subject I have got it right and my talent is in making it accessible, being warm about it, and not embarrassed about it."

Dr Boynton said: "To be a qualified professional in this field, your training has got to be done in a systematic, thoughtful, well-managed, supervised and organised way. It is not that Tracey Cox does not have something to contribute ... I think she is more than capable, she is an excellent flirt coach, but for the programme makers to rely on the fact that she has a background in psychology is incorrect." She claimed Sex Inspectors gave false hope: "People will initially think, 'This is the answer. This is going to help me save my marriage. Make me good in bed. Win my partner over.' But when they can't re-enact what they're told, they will assume there is something wrong with them and the psychological consequences of that can be devastating."

Mr Hodson accused Ms Cox of making "wild assertions" after he viewed one episode featuring a couple from Romford, in Essex. "How does she [Ms Cox] know that every woman wishes to be slurped like an ice cream?" he said, referring to one of the presenter's comments.

Paula Hall, a sexual and relationship psychotherapist for the charity Relate, said that by encouraging viewers to experiment, they risked greater sexual anxiety. "It is one thing to say 'make more of your cleavage' on a makeover programme ... but that is nowhere near as personal as telling someone to try something sexual. What happens when that person tries and it fails?"

The series was conceived by Daisy Goodwin, who has been behind a string of popular shows such as How Clean is Your House? It was based on another of her shows, The Dinner Party Inspectors.

Julian Bellamy, Channel 4's head of factual entertainment, said: "There are always people who see the word sex and will portray it as dumbing-down TV. This programme is intelligent, educational and informative."